Multicomponent Fiber Containing a Polyarylene Sulfide

ABSTRACT

A multicomponent fiber that contains two or more components arranged in distinct zones across the cross-section of the multicomponent fiber is provided. The components are arranged in a sheath/core configuration in which the core component is substantially surrounded by the sheath component. One of the sheath and the core is formed from a polyarylene sulfide composition and the other of the sheath and the core is formed from a thermoplastic composition that contains a thermoplastic polymer other than a polyarylene sulfide. Further, the polyarylene sulfide is “functionalized” in that it contains at least one functional group in its molecular structure (e.g., at its molecular terminal end). Without intending to be limited by theory, it is believed that such functional groups can improve the adhesion between the core and sheath components, thereby resulting in a fiber having improved thermal and mechanical properties.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Application Ser. No. 61/739,334 (filed on Dec. 19, 2012), which is incorporated herein in its entirety by reference thereto.

BACKGROUND OF THE INVENTION

Polyphenylene sulfide (“PPS”) is a high performance polymer that can withstand high thermal, chemical, and mechanical stresses. Due to its beneficial properties, various attempts have been made to form PPS fibers for use in various applications, such as garments. One drawback to PPS fibers, however, is that they are difficult to dye and can become compromised after exposure to ultraviolet light for a certain period of time. Light stabilizers can be employed to ameliorate this problem, but this is generally not an effective solution as the stabilizers are often easily removed during laundering. Attempts at solving these problems have involved the use of sheath/core bicomponent fibers in which PPS is used in a core and an additional polymer is used in a sheath. While addressing some of the issues with PPS fibers, these fibers may nevertheless possess poor thermal and mechanical properties due to the inherent incompatibility and poor adhesion between PPS and certain other types of thermoplastic polymers.

As such, a need currently exists for an improved polarylene sulfide fiber that can withstand high thermal, chemical, and mechanical stresses, but without a significant sacrifice in UV stability and dyeability.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a multicomponent fiber is disclosed that comprises a sheath component that substantially surrounds a core component. One of the sheath component and the core component is formed from a polyarylene sulfide composition that comprises a functionalized polyarylene sulfide, and the other of the sheath component and the core component is formed from a thermoplastic composition that contains a thermoplastic polymer other than a polyarylene sulfide.

Other features and aspects of the present invention are set forth in greater detail below.

BRIEF DESCRIPTION OF THE FIGURES

A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 is a transverse cross-sectional view of one embodiment of the multicomponent fiber of the present invention;

FIG. 2 is a cross-sectional view of another embodiment of the multicomponent fiber of present invention; and

FIG. 3 is a cross-sectional view of yet another embodiment of the multicomponent fiber of the present invention.

DETAILED DESCRIPTION

It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention.

Generally speaking, the present invention is directed to a multicomponent fiber (e.g., staple fibers, continuous filaments, etc.) that contains two or more components arranged in distinct zones across the cross-section of the multicomponent fiber. More particularly, the components are arranged in a sheath/core configuration in which the core component is substantially surrounded by the sheath component. One of the core component and the sheath component is formed from a polyarylene sulfide composition and other of the sheath component and the core component is formed from a thermoplastic composition, which contains a thermoplastic polymer other than a polyarylene sulfide. For instance, in one embodiment, the core component is formed of a polyarylene sulfide composition and the sheath component is formed of a thermoplastic composition that contains a thermoplastic polymer other than a polyarylene sulfide. In another embodiment, the sheath component is formed of a polyarylene sulfide composition and the core component is formed of a thermoplastic composition that contains a thermoplastic polymer other than a polyarylene sulfide.

The polyarylene sulfide composition is capable of providing a high degree of resistance to heat, chemicals, and mechanical stresses, which allows the resulting fiber to be used in a wide variety of applications. Moreover, in the embodiment in which it is contained within the core, the polyarylene sulfide composition is less likely to become compromised after exposure to ultraviolet light. The inclusion of the polyarylene sulfide composition within only the core component or the sheath component can also improve other aspects of the resulting fiber. For instance inclusion of the polyarylene sulfide in only the core or the sheath can alter dying characteristics. Inclusion of the polyarylene sulfide within only the core can allow the resulting fiber to be more readily dyed. Further, the polyarylene sulfide is also “functionalized” in that it contains at least one functional group in its molecular structure (e.g., at its molecular terminal end). Without intending to be limited by theory, it is believed that such functional groups can improve the adhesion between the core and sheath components, thereby resulting in a fiber having improved thermal and mechanical properties.

Various embodiments of the present invention will now be described in further detail.

I. Polyarylene Sulfide Composition A. Functionalized Polyarylene Sulfide

As indicated above, the polyarylene sulfide composition employed in the core component contains a functionalized polyarylene sulfide. The polyarylene sulfide may be a polyarylene thioether containing repeat units of the formula (I):

—[Ar¹)_(n)—X]_(m)—[(Ar²)_(i)—Y]_(j)—[(Ar³)_(k)—Z]_(l)—[(Ar⁴)_(o)—W]_(p)—  (I)

wherein Ar¹, Ar², Ar³, and Ar⁴ are the same or different and are arylene units of 6 to 18 carbon atoms; W, X, Y, and Z are the same or different and are bivalent linking groups selected from —SO₂—, —S—, —SO—, —CO—, —O—, —COO— or alkylene or alkylidene groups of 1 to 6 carbon atoms and wherein at least one of the linking groups is —S—; and n, m, i, j, k, l, o, and p are independently zero or 1, 2, 3, or 4, subject to the proviso that their sum total is not less than 2. The arylene units Ar¹, Ar², Ar³, and Ar⁴ may be selectively substituted or unsubstituted. Advantageous arylene systems are phenylene, biphenylene, naphthylene, anthracene and phenanthrene. The polyarylene sulfide typically includes more than about 30 mol %, more than about 50 mol %, or more than about 70 mol % arylene sulfide (—S—) units. In one embodiment the polyarylene sulfide includes at least 85 mol % sulfide linkages attached directly to two aromatic rings. In one embodiment, the polyarylene sulfide is a polyphenylene sulfide, defined herein as containing the phenylene sulfide structure —(C₆H₄—S)— (wherein n is an integer of 1 or more) as a component thereof.

Synthesis techniques that may be used in forming a polyarylene sulfide are generally known in the art. By way of example, a process for producing a polyarylene sulfide can include reacting a material that provides a hydrosulfide ion, e.g., an alkali metal sulfide, with a dihaloaromatic compound in an organic amide solvent. The alkali metal sulfide can be, for example, lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide or a mixture thereof. When the alkali metal sulfide is a hydrate or an aqueous mixture, the alkali metal sulfide can be processed according to a dehydrating operation in advance of the polymerization reaction. An alkali metal sulfide can also be generated in situ. In addition, a small amount of an alkali metal hydroxide can be included in the reaction to remove or react impurities (e.g., to change such impurities to harmless materials) such as an alkali metal polysulfide or an alkali metal thiosulfate, which may be present in a very small amount with the alkali metal sulfide.

The dihaloaromatic compound can be, without limitation, an o-dihalobenzene, m-dihalobenzene, p-dihalobenzene, dihalotoluene, dihalonaphthalene, methoxy-dihalobenzene, dihalobiphenyl, dihalobenzoic acid, dihalodiphenyl ether, dihalodiphenyl sulfone, dihalodiphenyl sulfoxide or dihalodiphenyl ketone. Dihaloaromatic compounds may be used either singly or in any combination thereof. Specific exemplary dihaloaromatic compounds can include, without limitation, p-dichlorobenzene; m-dichlorobenzene; o-dichlorobenzene; 2,5-dichlorotoluene; 1,4-dibromobenzene; 1,4-dichloronaphthalene; 1-methoxy-2,5-dichlorobenzene; 4,4′-dichlorobiphenyl; 3,5-dichlorobenzoic acid; 4,4′-dichlorodiphenyl ether; 4,4′-dichlorodiphenylsulfone; 4,4′-dichlorodiphenylsulfoxide; and 4,4′-dichlorodiphenyl ketone. The halogen atom can be fluorine, chlorine, bromine or iodine, and 2 halogen atoms in the same dihalo-aromatic compound may be the same or different from each other. In one embodiment, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene or a mixture of 2 or more compounds thereof is used as the dihalo-aromatic compound. As is known in the art, it is also possible to use a monohalo compound (not necessarily an aromatic compound) in combination with the dihaloaromatic compound in order to form end groups of the polyarylene sulfide or to regulate the polymerization reaction and/or the molecular weight of the polyarylene sulfide.

The polyarylene sulfide may be a homopolymer or may be a copolymer. By a suitable, selective combination of dihaloaromatic compounds, a polyarylene sulfide copolymer can be formed containing not less than two different units. For instance, in the case where p-dichlorobenzene is used in combination with m-dichlorobenzene or 4,4′-dichlorodiphenylsulfone, a polyarylene sulfide copolymer can be formed containing segments having the structure of formula (II):

and segments having the structure of formula (III):

or segments having the structure of formula (IV):

The polymerization reaction may be carried out in the presence of an organic amide solvent. Exemplary organic amide solvents used in a polymerization reaction can include, without limitation, N-methyl-2-pyrrolidone; N-ethyl-2-pyrrolidone; N,N-dimethylformamide; N,N-dimethylacetamide; N-methylcaprolactam; tetramethylurea; dimethylimidazolidinone; hexamethyl phosphoric acid triamide and mixtures thereof. The amount of the organic amide solvent used in the reaction can be, e.g., from 0.2 to 5 kilograms per mole (kg/mol) of the effective amount of the alkali metal sulfide.

The polyarylene sulfide may be linear, semi-linear, branched or crosslinked. A linear polyarylene sulfide includes as the main constituting unit the repeating unit of —(Ar—S)—. In general, a linear polyarylene sulfide may include about 80 mol % or more of this repeating unit. A linear polyarylene sulfide may include a small amount of a branching unit or a cross-linking unit, but the amount of branching or cross-linking units may be less than about 1 mol % of the total monomer units of the polyarylene sulfide. A linear polyarylene sulfide polymer may be a random copolymer or a block copolymer containing the above-mentioned repeating unit.

A semi-linear polyarylene sulfide may be utilized that has a cross-linking or branched structure provided by introducing into the polymer a small amount of one or more monomers having three or more reactive functional groups. For instance, between about 1 mol % and about 10 mol % of the polymer may be formed from monomers having three or more reactive functional groups. Methods that may be used in making semi-linear polyarylene sulfide are generally known in the art. By way of example, monomer components used in forming a semi-linear polyarylene sulfide can include an amount of polyhaloaromatic compounds having 2 or more halogen substituents per molecule which can be utilized in preparing branched polymers. Such monomers can be represented by the formula R′X_(n), where each X is selected from chlorine, bromine, and iodine, n is an integer of 3 to 6, and R′ is a polyvalent aromatic radical of valence n which can have up to about 4 methyl substituents, the total number of carbon atoms in R′ being within the range of 6 to about 16. Examples of some polyhaloaromatic compounds having more than two halogens substituted per molecule that can be employed in forming a semi-linear polyarylene sulfide include 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3-dichloro-5-bromobenzene, 1,2,4-triiodobenzene, 1,2,3,5-tetrabromobenzene, hexachlorobenzene, 1,3,5-trichloro-2,4,6-trimethylbenzene, 2,2′,4,4′-tetrachlorobiphenyl, 2,2′,5,5′-tetra-iodobiphenyl, 2,2′,6,6′-tetrabromo-3,3′,5,5′-tetramethylbiphenyl, 1,2,3,4-tetrachloronaphthalene, 1,2,4-tribromo-6-methylnaphthalene, and the like, and mixtures thereof.

The polymerization reaction apparatus for forming the polyarylene sulfide is not especially limited, although it is typically desired to employ an apparatus that is commonly used in formation of high viscosity fluids. Examples of such a reaction apparatus may include a stirring tank type polymerization reaction apparatus having a stirring device that has a variously shaped stirring blade, such as an anchor type, a multistage type, a spiral-ribbon type, a screw shaft type and the like, or a modified shape thereof. Further examples of such a reaction apparatus include a mixing apparatus commonly used in kneading, such as a kneader, a roll mill, a Banbury mixer, etc. Following polymerization, the molten polyarylene sulfide may be discharged from the reactor, typically through an extrusion orifice fitted with a die of desired configuration, cooled, and collected. Commonly, the polyarylene sulfide may be discharged through a perforated die to form strands that are taken up in a water bath, pelletized and dried. The polyarylene sulfide may also be in the form of a strand, granule, or powder.

The molecular weight of the polyarylene sulfide is not particularly limited, though in one embodiment, the polyarylene sulfide (which can also encompass a blend of one or more polyarylene sulfide polymers and/or copolymers) may have a relative high molecular weight. For instance a polyarylene sulfide may have a number average molecular weight greater than about 25,000 g/mol, or greater than about 30,000 g/mol, and a weight average molecular weight greater than about 60,000 g/mol, or greater than about 65,000 g/mol.

As noted above, the polyarylene sulfide is “functionalized” to the extent that it contains at least one functional group in its molecular structure. The functional group may include, for example, an epoxy group, hydroxyl group, carboxyl, acrylate group, carbonate group, amino group, nitro group, etc., as well as combinations thereof. A variety of different techniques may generally be employed to incorporate a functional group into the molecular structure of a polyarylene sulfide. For example, the reactants used to form the polymer, such as described above, may possess the desired functional group. In other embodiments, however, the functional group is introduced by reacting a base polyarylene sulfide with a functional compound.

For example, a base polyarylene sulfide can be reacted with a disulfide compound, which can lead to addition of the reactive functional groups of the disulfide compound to the polyarylene sulfide backbone. The reaction can occur in a variety of ways, such as during melt processing of the polymer and disulfide compound. The disulfide compound may, for instance, have the structure of formula (V):

R¹—S—S—R²  (V)

wherein R¹ and R² may be the same or different and are hydrocarbon groups that independently include from 1 to about 20 carbons. For instance, R¹ and R² may be an alkyl, cycloalkyl, aryl, or heterocyclic group. In addition, at least one of R¹ and R² has a reactive functionality at terminal end(s) of the disulfide compound. For example, at least one of R¹ and R² may include a terminal epoxy group, hydroxyl group, carboxyl group, acrylate group, carbonate group, amino group, etc. Examples of disulfide compounds including reactive terminal groups as may be combined with a polyarylene sulfide may include, without limitation, 2,2′-diaminodiphenyl disulfide, 3,3′-diaminodiphenyl disulfide, 4,4′-diaminodiphenyl disulfide, dibenzyl disulfide, dithiosalicyclic acid, dithioglycolic acid, α,α′-dithiodilactic acid, β,β′-dithiodilactic acid, 3,3′-dithiodipyddine, 4,4′dithiomorpholine, 2,2′-dithiobis(benzothiazole), 2,2′-dithiobis(benzimidazole), 2,2′-dithiobis(benzoxazole) and 2-(4′-morpholinodithio)benzothiazole. To impart the desired reactivity, the weight ratio of the amount of the polyarylene sulfide to the amount of the disulfide compound is typically from about 1000:1 to about 10:1, from about 500:1 to about 20:1, or from about 400:1 to about 30:1.

B. Optional Additives

If desired, the functionalized polyarylene sulfide may constitute the entire polyarylene sulfide component. In other cases, however, one or more optional additives may also be employed in the composition for a variety of different purposes. Functionalized polyarylene sulfides may nevertheless constitute from about 60 wt. % to 100 wt. % (e.g., 100 wt. %), in some embodiments from about 75 wt. % to about 99.5 wt. %, and in some embodiments, from about 85 wt. % to about 99 wt. % of the polyarylene sulfide composition used in the core component or the sheath component of the fiber. When employed, the optional additives may likewise constitute from about 0.1 wt. % to about 40 wt. %, in some embodiments from about 0.5 wt. % to about 25 wt. %, and in some embodiments, from about 1 wt. % to about 15 wt. % of the polyarylene sulfide composition.

Any suitable additive may generally be employed in the composition. For example, in one embodiment, the polyarylene sulfide composition can include a UV stabilizer. One particularly suitable UV stabilizer that may be employed is a hindered amine UV stabilizer. Suitable hindered amine UV stabilizer compounds may be derived from a substituted piperidine, such as alkyl-substituted piperidyl, piperidinyl, piperazinone, alkoxypiperidinyl compounds, and so forth. For example, the hindered amine may be derived from a 2,2,6,6-tetraalkylpipendinyl. The hindered amine may, for example, be an oligomeric or polymeric compound having a number average molecular weight of about 1,000 or more, in some embodiments from about 1000 to about 20,000, in some embodiments from about 1500 to about 15,000, and in some embodiments, from about 2000 to about 5000. Such compounds typically contain at least one 2,2,6,6-tetraalkylpiperidinyl group (e.g., 1 to 4) per polymer repeating unit. One particularly suitable high molecular weight hindered amine is commercially available from Clariant under the designation Hostavin® N30 (number average molecular weight of 1200). Another suitable high molecular weight hindered amine is commercially available from Adeka Palmarole SAS under the designation ADK STAB® LA-63 and ADK STAB LA-68. Yet other examples of suitable high molecular weight hindered amines include, for instance, an oligomer of N-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol and succinic acid (Tinuvin® 622 from Ciba Specialty Chemicals, MW=4000); oligomer of cyanuric acid and N,N-di(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylene diamine; poly((6-morpholine-S-triazine-2,4-diyl)(2,2,6,6-tetramethyl-4-piperidinyl)-iminohexamethylene-(2,2,6,6-tetramethyl-4-piperidinyl)-imino) (Cyasorb® UV 3346 from Cytec, MW=1600); polymethylpropyl-3-oxy-[4(2,2,6,6-tetramethyl)-piperidinyl)-siloxane (Uvasil® 299 from Great Lakes Chemical, MW=1100 to 2500); copolymer of α-methylstyrene-N-(2,2,6,6-tetramethyl-4-piperidinyl)maleimide and N-stearyl maleimide; 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol tetramethyl-polymer with 1,2,3,4-butanetetracarboxylic acid; and so forth.

In addition to the high molecular weight hindered amines, low molecular weight hindered amines may also be employed. Such hindered amines are generally monomeric in nature and have a molecular weight of about 1000 or less, in some embodiments from about 155 to about 800, and in some embodiments, from about 300 to about 800. Specific examples of such low molecular weight hindered amines may include, for instance, bis-(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin® 770 from Ciba Specialty Chemicals, MW=481); bis-(1,2,2,6,6-pentamethyl-4-piperidinyl)-(3,5-ditert.butyl-4-hydroxybenzyl)butyl-propane dioate; bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro-(4,5)-decane-2,4-dione; butanedioic acid-bis-(2,2,6,6-tetramethyl-4-piperidinyl) ester; tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate; 7-oxa-3,20-diazadispiro(5.1.11.2) heneicosan-20-propanoic acid, 2,2,4,4-tetramethyl-21-oxo, dodecyl ester; N-(2,2,6,6-tetramethyl-4-piperidinyl)-N′-amino-oxamide; o-t-amyl-o-(1,2,2,6,6-pentamethyl-4-piperidinyl)-monoperoxi-carbonate; β-alanine, N-(2,2,6,6-tetramethyl-4-piperidinyl), dodecylester; ethanediamide, N-(1-acetyl-2,2,6,6-tetramethylpipedinyl)-N′-dodecyl; 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidinyl)-pyrrolidin-2,5-dione; 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidinyl)-pyrrolidin-2,5-dione; 3-dodecyl-1-(1-acetyl,2,2,6,6-tetramethyl-4-piperidinyl)-pyrrolidin-2,5-dione; (Sanduvar® 3058 from Clarant, MW=448.7); 4-benzoyloxy-2,2,6,6-tetramethylpiperidine; 1-[2-(3,5-di-tert-butyl-4-hydroxyphenylpropionyloxy)ethyl]-4-(3,5-di-tert-butyl-4-hydroxylphenyl propionyloxy)-2,2,6,6-tetramethyl-piperidine; 2-methyl-2-(2″,2″,6″,6″-tetramethyl-4-piperidinylamino)-N-(2′,2′,6′,6′-tetra-methyl-4′-piperidinyl) propionylamide; 1,2-bis-(3,3,5,5-tetramethyl-2-oxo-piperazinyl)ethane; 4-oleoyloxy-2,2,6,6-tetramethylpiperidine; and combinations thereof.

Other suitable UV stabilizers may include UV absorbers, such as benzotriazoles or benzopheones, which can absorb UV radiation. Suitable benzotriazoles may include, for instance, 2-(2-hydroxyphenyl)benzotriazoles, such as 2-(2-hydroxy-5-methylphenyl)benzotriazole; 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole (Cyasorb® UV 5411 from Cytec); 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzo-triazole; 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenyl ethyl)phenol; 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole; 2-(2-hydroxy-3,5-dicumylphenyl)benzotriazole; 2,2′-methylenebis(4-tert-octyl-6-benzo-triazolylphenol); polyethylene glycol ester of 2-(2-hydroxy-3-tert-butyl-5-carboxyphenyl)benzotriazole; 2-[2-hydroxy-3-(2-acryloyloxyethyl)-5-methylphenyl]-benzotriazole; 2-[2-hydroxy-3-(2-methacryloyloxyethyl)-5-tert-butylphenyl]benzotriazole; 2-[2-hydroxy-3-(2-methacryloyloxyethyl)-5-tert-octylphenyl]benzotriazole; 2-[2-hydroxy-3-(2-methacryloyloxyethyl)-5-tert-butylphenyl]-5-chlorobenzotriazole; 2-[2-hydroxy-5-(2-methacryloyloxyethyl)phenyl]benzotriazole; 2-[2-hydroxy-3-tert-butyl-5-(2-methacryloyloxyethyl)phenyl]benzotriazole; 2-[2-hydroxy-3-tert-amyl-5-(2-methacryloyloxyethyl)phenyl]benzotriazole; 2-[2-hydroxy-3-tert-butyl-5-(3-methacryloyloxypropyl)phenyl]-5-chlorobenzotriazole; 2-[2-hydroxy-4-(2-methacryloyloxymethyl)phenyl]benzotriazole; 2-[2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropyl)phenyl]benzotriazole; 2-[2-hydroxy-4-(3-methacryloyl-oxypropyl)phenyl]benzotriazole; and combinations thereof. Exemplary benzophenone light stabilizers may likewise Include 2-hydroxy-4-dodecyloxybenzophenone; 2,4-dihydroxybenzophenone; 2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate (Cyasorb® UV 209 from Cytec); 2-hydroxy-4-n-octyloxy)benzophenone (Cyasorb® 531 from Cytec); 2,2′-dihydroxy-4-(octyloxy)benzophenone (Cyasorb® UV 314 from Cytec); hexadecyl-3,5-bis-tert-butyl-4-hydroxybenzoate (Cyasorb® UV 2908 from Cytec); 2,2′-thiobis(4-tert-octylphenolato)-n-butylamine nickel(II) (Cyasorb® UV 1084 from Cytec); 3,5-di-tert-butyl-4-hydroxybenzoic acid, (2,4-di-tert-butylphenyl)ester (Cyasorb® 712 from Cytec); 4,4′-dimethoxy-2,2′-dihydroxybenzophenone (Cyasorb® UV 12 from Cytec); and combinations thereof.

Still other additives that can be included in the polyarylene sulfide composition can encompass, without limitation, fillers, lubricants, antimicrobials, antioxidants, other types of stabilizers, surfactants, waxes, flow promoters, solid solvents, and other materials added to enhance properties and processibility. Such optional materials may be employed in the composition in conventional amounts.

II. Thermoplastic Composition

As Indicated above, either the core component or the sheath component of the fiber is formed from a thermoplastic composition that contains a polymer other than a polyarylene sulfide. The polymer may, for instance, be a high melting point thermoplastic polymer, such as those having a melting point of about 150° C. or more, in some embodiments from about 160° C. to about 280° C., and in some embodiments, from about 180° C. to about 260° C. Examples of such polymers may include, for instance, aromatic polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene terephthalate, etc.), aliphatic polyesters (e.g., polylactic acid), polyamides (e.g., Nylon 6, Nylon 66, etc.), polyolefins (e.g., polypropylene), and so forth.

If desired, the entire composition used to form the component that is not formed of the polyarylene sulfide composition may be formed from thermoplastic polymers, such as those described above. Of course, one or more optional additives may also be employed in the composition for a variety of different purposes. The additives may be the same or different than those described above. In certain embodiments, for example, UV blockers may be employed in the thermoplastic composition to help reduce the likelihood that the composition in both the core and the sheath is exposed to ultraviolet light. Particularly suitable UV blockers are inorganic oxides of one or more of Ce, Zn, Bi, Ti, Sn and/or Sb. Examples of such inorganic UV blockers may include, for instance, zinc oxide, titanium dioxide, etc.

The thermoplastic polymers generally constitute from about 60 wt. % to 100 wt. % (e.g., 100 wt. %), in some embodiments from about 75 wt. % to about 99.5 wt. %, and in some embodiments, from about 85 wt. % to about 99 wt. % of the component of the fiber formed of the thermoplastic composition that is generally free of any polyarylene sulfide. When employed, the optional additives may likewise constitute from about 0.1 wt. % to about 40 wt. %, in some embodiments from about 0.5 wt. % to about 25 wt. %, and in some embodiments, from about 1 wt. % to about 15 wt. % of the composition. Regardless, it is desired that the thermoplastic composition is generally free of polyarylene sulfides. In this manner, the fiber may be better able to withstand exposure to ultraviolet light, and in one embodiment may also be more readily dyed. For instance, the thermoplastic composition may contain polyarylene sulfides in an amount of about 10 wt. % or less, in some embodiments about 5 wt. % or less, and in some embodiments, about 1 wt. % or less (e.g., 0 wt. %).

III. Fiber Configuration

The nature of the sheath/core fiber may generally vary as is well known in the art. For example, although not required, the components of the fiber are typically arranged in a concentric configuration in which the sheath component has a substantially uniform thickness, such that the core component lies approximately in the center of the fiber. This is in contrast to an eccentric configuration, in which the thickness of the sheath component varies, and the core component therefore does not lie in the center of the fiber. Concentric sheath/core fibers can be defined as fibers in which the center of the core component is biased by no more than about 20%, and in some embodiments, no more than about 10% based on the diameter of the sheath/core bicomponent fiber, from the center of the sheath component. Islands in the sea and multi-lobal fibers of the invention can also include a concentric core component substantially centrally positioned within the fiber structure. Alternatively, the additional polymeric components can be eccentrically located so that the thickness of the surrounding sheath component varies across the cross-section of the fiber.

The number of components of the fiber may also vary, such as 2 or more, and in some embodiments, from 2 to 3. For purposes of illustration only, the present invention will generally be described in terms of a bicomponent fiber having two components. However, it should be understood that the scope of the present invention is meant to include fibers with two or more structured components. Referring to FIG. 1, for example, a bicomponent fiber 10 is shown that has an inner core component 12 and a surrounding sheath component 14. In one embodiment, the core component is formed of a polyarylene sulfide polymer composition while the sheath component 14 is formed from the thermoplastic composition, such as described above. In another embodiment, the compositions are switched such that the core component is formed of a thermoplastic composition as described above and the sheath component is formed of a polyarylene sulfide polymer composition. The sheath component 14 is typically continuous, e.g., completely surrounds the core component 12 and forms the entire outer surface of the fiber 10. The core component 12 can be concentric as illustrated in FIG. 1 or eccentric.

Other structured fiber configurations as known in the art can also be used. FIG. 2, for instance, illustrates one embodiment of an islands-in-the-sea fiber 20. Generally, such fibers include a “sea” sheath component 22 surrounding a plurality of “island” core components 24. The island components can be substantially uniformly arranged within the matrix of sea component 22, such as illustrated in FIG. 2. Alternatively, the island components can be randomly distributed within the sea matrix. The sea component 22 typically forms the entire outer exposed surface of the fiber and is formed of a thermoplastic composition, such as described above. As with the core component 12 shown in FIG. 1, the island components 24 may be formed from the polyarylene sulfide composition of the present invention and the sea components 22 can be formed of the thermoplastic composition or vice versa in another embodiment. The fiber can optionally also include a central core 26, which can be concentric as Illustrated or eccentric, and can be formed from either the polyarylene sulfide composition or the thermoplastic composition, in various embodiments.

The fibers of the invention may also be multilobal fibers having arms or lobes (e.g., two or more) extending outwardly from a central portion thereof. Referring to FIG. 3, for instance, one embodiment of a multilobal fiber 30 is shown that includes a central portion 32 and arms or lobes 34 extending outwardly therefrom. The arms or lobes 34 may be formed of the thermoplastic composition and the central portion 32 may be formed of the polyarylene sulfide composition (or vice versa). Although illustrated in FIG. 3 as a centrally located core, it can also be eccentric.

Regardless of the particular configuration, the relative weight percentages of the core and sheath components of the fiber may generally vary. For example, the core component may constitute from about 30 wt. % to about 99 wt. %, in some embodiments from about 40 wt. % to about 98 wt. %, and in some embodiments, from about 50 wt. % to about 95 wt. % of the fiber, while the sheath component may constitute from about 1 wt. % to about 70 wt. %, in some embodiments from about 2 wt. % to about 60 wt. %, and in some embodiments, from about 5 wt. % to about 50 wt. % of the fiber.

Any of a variety of different techniques may generally be employed to form multicomponent fibers as is well known in the art, such as described in U.S. Pat. No. 4,816,335 to Kouvama. et al.; U.S. Pat. No. 5,178,813 to Akatsu, et al.; U.S. Pat. No. 5,372,760 to Wellenhofer. et al. and U.S. Pat. No. 7,931,843 to Krins. et al. For example, the polymer compositions may be melt extruded separately and fed into a polymer distribution system wherein the polymers are introduced into a spinneret plate. The polymer compositions can follow separate paths to the fiber spinneret and combined in a spinneret hole. The spinneret may be configured so that the extrudate has the desired shape. Following extrusion through the die, the resulting thin fluid strands, or filaments, may remain in the molten state before they are solidified by cooling in a surrounding fluid medium, which may be chilled air blown through the strands, or immersion on a bath of liquid such as water. Once solidified, the strands are taken up on a godet or another take-up surface. In a continuous filament process, the strands are taken up on a godet which draws down the thin fluid streams in proportion to the speed of the take-up godet. In a spunbond process, the strands are collected in a jet, such as for example, an air gun, and blown onto a take-up surface such as a roller or a moving belt to form a spunbond web. In a meltblown process, air is ejected at the surface of the spinneret, which serves to simultaneously draw down and cool the thin fluid streams as they are deposited on a take-up surface in the path of cooling air, thereby forming a fiber web.

Regardless of the type of melt spinning procedure that is used, the thin fluid streams are melt drawn down in a molten state, e.g., before solidification occurs to orient the polymer molecules for good tenacity. Typical melt draw down ratios known in the art may be utilized. Where a continuous filament or staple process is employed, it may be desirable to draw the strands in the solid state with conventional drawing equipment, such as, for example, sequential godets operating at differential speeds. Following drawing in the solid state, the continuous filaments may be crimped or texturized and cut into a desirable fiber length, thereby producing staple fiber. The length of the staple fibers generally ranges from about 25 to about 50 millimeters, although the fibers can be longer or shorter as desired.

IV. Fibrous Materials

The fibers may be employed in their individual form (e.g., individual staple fibers or filaments) or in the form of a fibrous material, such as yarns, fabrics, or articles (e.g., garments). Yarns may include, for instance, multiple staple fibers that are twisted together (“spun yarn”), filaments laid together without twist (“zero-twist yarn”), (3) filaments laid together with a degree of twist, (4) a single filament with or without twist (“monofilament”), etc. The yarn may or may not be texturized. Suitable fabrics may likewise include, for instance, woven fabrics, knit fabrics, nonwoven fabrics, etc. The multicomponent fibers of the present invention may be used to form at least a portion of the fibers of the yarn and/or fabric. In certain embodiments, for instance, substantially all of the fibers of the yarn and/or fabric are formed in accordance with the present invention. In other embodiments, however, additional fibers (staple fibers or filaments) can be employed in combination with the multicomponent fibers. Such additional fibers may include, for instance, are natural fibers, such as cotton, wool, bast, silk, etc., and/or synthetic fibers, such as aromatic polyamides (e.g., meta-aramids (e.g., Nomex® or Kevlar®), para-aramids, etc.), aliphatic polyamides (e.g., nylon), polyesters, polybenzimidazole (“PBI”), polybenzoxazole (“PBO”), polypyridobisimidazole (“PIPD”), rayon, melamine, acetate, lyocell, etc., as well as combinations of two or more types of natural and/or synthetic fibers.

In one embodiment the polyarylene sulfide polymer composition is generally kept within the core component, and the resulting fiber or fibrous material is able to be easily dyed. In this regard, the fiber can be subjected to one or more dyeing operations in which it is contacted with a disperse dye. Suitable disperse dyes may include those described in “Disperse Dyes” in the Color Index, 3^(rd) edition. Such dyes include, for example, carboxylic acid group-free and/or sulfonic acid group-free nitro, amino, aminoketone, ketoninime, methine, polymethine, diphenylamine, quinoline, benzimidazole, xanthene, oxazine and coumarin dyes and especially anthraquinone and azo dyes, such as mono- or di-azo dyes. Disperse dyes are also described in detail in U.S. Patent Publication No. 2006/0048308. For instance, primary red color disperse dyes may include Disperse Red 60 (Intrasil Brilliant Red 2B 200%), Disperse Red 50 (Intrasil Scarlet 2 GH), Disperse Red 146 (Intrasil Red BSF), Disperse Red 127 (Dianix Red BSE), Dianix Red ACE, Disperse Red 65 (Intrasil Red MG), Disperse Red 86 (Terasil Pink 2 GLA), Disperse Red 191 (Intrasil Pink SRL), Disperse Red 338 (Intrasil Red 4BY), Disperse Red 302 (Tetrasil Pink 3G), Disperse Red 13 (Intrasperse Bordeaux BA), Disperse Red 167 (Foron Rubine S-2GFL), Disperse Violet 26 (Intrasil Violet FRL), etc.; primary blue color disperse dyes may include Disperse Blue 60 (Terasil Blue BGE 200%), Disperse Blue 291 (Intrasil Blue MGS), Disperse Blue 118 (Terasil Blue GBT), Terasil Blue HLB, Dianix Blue ACE, Disperse Blue 87 (Intrasil Blue FGB), Disperse Blue 148 (Palnnil Dark blue 3RT), Disperse Blue 56 (Intrasil Blue FBL), Disperse Blue 332 (Bafixan Turquoise 2 BL liq.), etc.; and primary yellow color dyes may include Disperse Yellow 64 (Disperte Yellow 3G 200%), Disperse Yellow 23 (Intrasil Yellow 5R), Palanil Yellow HM, Disperse Brown 19 (Dispersol Yellow D-7G), Disperse Orange 30 (Foron Yellow Brown S-2RFL), Disperse Orange 41 (Intrasil Orange 4RL), Disperse Orange 37 (Intrasil Dark Orange 3 GH), Disperse Yellow 3, Disperse Orange 30, Disperse Yellow 42, Disperse Orange 89, Disperse Yellow 235, Disperse Orange 3, Disperse Yellow 54, Disperse Yellow 233 (Foron Yellow S-6GL), etc.

The fiber may be contacted with the disperse dye by immersing it in a bath (e.g., aqueous bath) that contains the dye. The weight ratio of the dye bath to the fabric (also known as the “liquor ratio”) is typically from about 5 to about 30, in some embodiments from about 8 to about 25, and in some embodiments, from about 10 to about 20. Regardless, disperse dyes typically constitute, for example, from about 0.01 wt. % to about 15 wt. %, and in some embodiments, from about 0.5 wt. % to about 5 wt. %. of the bath in which it is employed. The lower concentrations of the dye in are useful for tinting operations, while higher dye concentrations produce a more intense color. Other components may also be employed in the dye bath, such as light stabilizers, surfactants, optical brighteners, fabric softeners, antistatic agents, antibacterial agents, anti-wrinkling agents, ironing aids, flame-retardants, enzymes, anti-foaming agents, fragrances, etc. In certain embodiments, for example, a light stabilizer is employed in the bath.

The dye bath may be contacted with the fibers at temperatures of from about 15° C. to about 150° C., in some embodiments from about 20° C. to about 130° C., and in some embodiments, from about 20° C. to about 30° C. Under such mild temperature conditions, dyeing can still be readily carried out at atmospheric pressure. The pH of the dye bath is also typically in the range of from about 3 to about 8, and in some embodiments, from about 4 to about 7. Dyeing may be carried out using either batch or continuous operations. If a batch method is employed, the fibrous material is typically contacted with the dye bath for a period of from about 0.25 to about 3 hours, and in some embodiments, from about 0.5 to about 1.0 hour.

The color of the dyed fibrous material may be substantially different than the original fibrous material, even after laundering and/or aging in ultraviolet light for a certain period of time (e.g., 20 hours). This difference in color can be quantified by measuring the absorbance with an optical reader in accordance with a standard test methodology known as “CIELAB”, which is described in Pocket Guide to Digital Printing by F. Cost, Delmar Publishers, Albany, N.Y. ISBN 0-8273-7592-1 at pages 144 and 145 and “Photoelectric color difference meter”, Journal of Optical Society of America, volume 48, page numbers 985-995, S. Hunter, (1958), both of which are incorporated herein by reference in their entirety. More specifically, the CIELAB test method defines three “Hunter” scale values, L*, a*, and b*, which correspond to three characteristics of a perceived color based on the opponent theory of color perception and are defined as follows:

L*=Lightness (or luminosity), ranging from 0 to 100, where 0=dark and 100=light;

a*=Red/green axis, ranging from −100 to 100; positive values are reddish and negative values are greenish; and

b*=Yellow/blue axis, ranging from −100 to 100; positive values are yellowish and negative values are bluish.

Color measurement can be performed using a DataColor 650 Spectrophotometer utilizing an integrating sphere with measurements made using the specular included mode. Color coordinates can likewise be calculated according to ASTM D2244-11 under an illuminant D65/10°, A/10°, or F2/10° observer, using CIELAB units. Because CIELAB color space is somewhat visually uniform, a single number may be calculated that represents the total absolute color difference between two colors as perceived by a human using the following equation:

ΔE=[(ΔL*)²+(Δa*)²+(Δb)₂]^(1/2)

wherein, ΔL* is the luminosity value of a first color subtracted from the luminosity value of a second color, Δa* is the red/green axis value of the first color subtracted from the red/green axis value of the second color; and Δb* is the yellow/blue axis value of the first color subtracted from the yellow/blue axis value of the second color. In CIELAB color space, each ΔE unit is approximately equal to a “just noticeable” difference between two colors and is therefore a good measure for an objective device-independent color specification system that may be used for the purpose of expressing differences in color. For instance, the “first color” in the formula above may represent the color of the undyed fibrous material and the “second color” may represent the color of the dyed fibrous material. In the present invention, the resulting ΔE values may be relatively large, such as about 5 or more, in some embodiments about 10 more, and in some embodiments, about 20 more. The dyed fibrous material may possess, for instance, a lightness (L*) of 50 to 120, a green-red (a*) of −20 to 20, and a blue-yellow (b*) of −20 to 20. Notably, such ΔE values may even be maintained after exposure of the materials to ultraviolet light for a certain period of time, such as about 20 hours.

V. Articles

The fibers and fibrous materials of the present invention may generally be employed in a wide variety of different articles. For example, due to the heat resistance of polyarylene sulfides, the fibers may be particularly well suited in articles in which flame retardancy and/or chemical resistance are desired. Such articles may include, for instance, protective garments, gloves, aprons, coveralls, boots, hoods, sleepware, etc. For example, a garment that protects firefighters against heat, flame and electric arc in fighting structural fires is known as a “turnout” coat. Such coats may be formed from one or multiple layers, such as a thermal liner that faces the wearer, an outer shell, a moisture barrier positioned between the thermal liner and outer shell. Any layer of the coat may contain the fibers of the present invention. Regardless of the particular types of articles in which it is employed, the fibers of the present invention may exhibit flame retardant properties without the need for conventional flame retardants, such as phosphoric compounds (e.g., phosphinic acid salts), nitrogen-containing synergists (e.g., melamine, melamine cyanurate, etc.), and so forth. In fact, the fibers can be substantially free of flame retardants in that they constitute no more than about 5 wt. %, in some embodiments no more than about 2 wt. %, and in some embodiments, no more than about 0.5 wt. % of the fibrous material. Of course, it should be understood that in certain alternative embodiments, flame retardants may be employed in higher percentages if desired.

These and other modifications and variations of the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims. 

What is claimed is:
 1. A multicomponent fiber that comprises a sheath component that substantially surrounds a core component, wherein one of the core component and the sheath component is formed from a polyarylene sulfide composition that comprises a functionalized polyarylene sulfide, and wherein the other of the sheath component and the core component is formed from a thermoplastic composition that contains a thermoplastic polymer other than a polyarylene sulfide.
 2. The multicomponent fiber of claim 1, wherein the core component is formed from the polyarylene sulfide composition and the sheath component is formed from the thermoplastic composition that contains a thermoplastic polymer other than a polyarylene sulfide.
 3. The multicomponent fiber of claim 1, wherein the sheath component is formed from the polyarylene sulfide composition and the core component is formed from the thermoplastic composition that contains a thermoplastic polymer other than a polyarylene sulfide.
 4. The multicomponent fiber of claim 1, wherein the functionalized polyarylene sulfide is a functionalized polyphenylene sulfide.
 5. The multicomponent fiber of claim 1, wherein the functionalized polyarylene sulfide contains at least one functional group in its molecular structure.
 6. The multicomponent fiber of claim 5, wherein the functional group is an epoxy group, hydroxyl group, carboxyl, acrylate group, carbonate group, amino group, nitro group, or a combination thereof.
 7. The multicomponent fiber of claim 5, wherein the functional group is introduced by reacting a base polyarylene sulfide with a functional disulfide compound.
 8. The multicomponent fiber of claim 7, wherein the disulfide compound has the following general structure: R¹—S—S—R² wherein R¹ and R² are independently hydrocarbon groups that include from 1 to about 20 carbons, and wherein at least one of R¹ and R² has a reactive functionality.
 9. The multicomponent fiber of claim 7, wherein the disulfide compound is 2,2′-diaminodiphenyl disulfide, 3,3′-diaminodiphenyl disulfide, 4,4′-diaminodiphenyl disulfide, dibenzyl disulfide, dithiosalicyclic acid, dithioglycolic acid, α,α′-dithiodilactic acid, β,β′-dithiodilactic acid, 3,3′-dithiodipyridine, 4,4′-dithiomorpholine, 2,2′-dithiobis(benzothiazole), 2,2′-dithiobis(benzimidazole), 2,2′-dithiobis(benzoxazole), 2-(4′-morpholinodithio)benzothiazole, or a combination thereof.
 10. The multicomponent fiber of claim 1, wherein the polyarylene sulfide composition contains from about 60 wt. % to 100 wt. % of functionalized polyarylene sulfides.
 11. The multicomponent fiber of claim 1, wherein the thermoplastic polymer has a melting point of about 150° C. or more.
 12. The multicomponent fiber of claim 1, wherein the thermoplastic polymer is an aromatic polyester, aliphatic polyester, polyamide, polyolefin, or a combination thereof.
 13. The multicomponent fiber of claim 1, wherein the thermoplastic composition comprises from about 60 wt. % to 100 wt. % of thermoplastic polymers.
 14. The multicomponent fiber of claim 1, wherein the thermoplastic composition further comprises a UV blocker.
 15. The multicomponent fiber of claim 1, wherein the thermoplastic composition is generally free of polyarylene sulfides.
 16. The multicomponent fiber of claim 1, wherein the sheath and core components are arranged in a concentric configuration.
 17. The multicomponent fiber of claim 1, wherein the sheath and core components are arranged in an eccentric configuration.
 18. The multicomponent fiber of claim 1, wherein the fiber has an islands-in-the-sea configuration in which the sea is the sheath component and the islands are the core component.
 19. The multicomponent fiber of claim 1, wherein the fiber has a multilobal configuration in which arms extend outwardly from a central portion, wherein the sheath component forms the arms and the core component forms the central portion.
 20. The multicomponent fiber of claim 1, wherein the fiber is a bicomponent fiber.
 21. The multicomponent fiber of claim 1, wherein the core component constitute from about 30 wt. % to about 99 wt. % of the fiber and the sheath component constitutes from about 1 wt. % to about 70 wt. % of the fiber.
 22. A fibrous material comprising the multicomponent fiber of claim
 1. 